This invention relates to an ignition system for garden tractors or the like, and more particularly, to a single switch interlock which prevents the tractor engine from starting when either the mower drive or transmission drive controls are in their engaged positions.
Ignition systems for garden tractors or the like are known which make the tractor electrical starting circuit inoperative under certain conditions. in U.S. Pat. No. 3,534,637, assigned to the assignee of the present invention, a mechanism is disclosed for rendering the starting circuit of the vehicle inoperative whenever the vehicle transmission is in its engaged position. The mechanism includes a switch incorporated into the starting circuit which is opened in response to movement of the shifting device for the transmission from a neutral to an engaged position. Another ignition interlock system is disclosed in U.S. Pat. No. 3,569,726, also assigned to the assignee of the present invention, which makes the tractor electrical system inoperative as soon as the operator removes his weight from the tractor seat. A plurality of electrical switches are connected in the circuit to electrically by-pass the seat-operated switch at the discretion of the operator.
There are disadvantages to the prior art type of start systems described. The vehicle transmission type requires relatively precise adjustment of the linkages, and there is no provision for making the starting circuit inoperative if a mower drive or the like is engaged in addition to the transmission. The seat-operated type requires a plurality of switches to operate the system when the operator is not in his seat. Thus, there has been a need for a simplified ignition system control device which is capable of preventing the tractor engine from starting when more than one drive control is engaged.
It is desirable to incorporate mechanism into the tractor starting system that will prevent the tractor engine from starting if either the transmission or mower drive is engaged. The prior art mechanisms proposed, including the ones discussed, have been expensive, are difficult to install and maintain, and are capable of being readily rendered inoperative. Thus, the disadvantages in present ignition system control devices have resulted in the single switch interlock of the present invention which prevents the tractor engine from starting when either the mower drive or transmission drive controls are in their engaged positions.